Different Types of Composting: Is Aerobic or Anaerobic Composting Better?

With many different methods of composting, how do you know which one to choose? To begin with, it’s helpful to note that all composting methods fall under one of two types of composting: Aerobic composting and Anaerobic composting. The difference is simply whether or not they require air for the decomposition process.

In this article I look deeper into what aerobic (with air) and anaerobic (without air) composting is, their pros and cons, and which type of composting could be right for you.

Benefits of Composting

Composting is a natural process that involves the breakdown of organic matter such as leaves and food scraps, turning it into nutrient-rich fertilizer for the soil.

Composting has several benefits both for the soil and the environment, these include:

• Improving soil health
• Reducing landfill waste
• Saving natural resources
• Promoting biodiversity that attracts worms, helping with the decomposition process, and creating healthy soil.

There are different types of composting methods and choosing the right one can be confusing.

First, I’ll explain the two primary types of composting: aerobic and anaerobic, and how to decide which method of composting is right for you.

Different Types of Aerobic & Anaerobic Composting Methods

AEROBIC COMPOSTING	ANAEROBIC COMPOSTING
Traditional Composting (Compost Bins)	Pit Composting
Hot Composting	Bokashi Composting
Vermicomposting (Worm Faming)

Aerobic vs Anaerobic Bacteria

Before we begin, a quick biology lesson…

Within the soil are billions of tiny microbes continually working to break down organic matter.

Keep these microbes happy and they’ll thrive, working faster. Deprive them of their basic needs and the opposite occurs.

The faster these microbes work, the more heat is produced and the more efficient the decomposition process.

When it comes to composting there are two types of microbes/bacteria- anaerobic and aerobic. For aerobic bacteria to work at their peak, they require plenty of oxygen. On the contrary, anaerobic bacteria are in their happy place with as little oxygen as possible!

Understanding this key difference between aerobic and anaerobic bacteria is important as it will help you optimise your composting method of choice.

What is Aerobic Composting

Aerobic composting is one of the two main types of composting that relies on the presence of oxygen to break down organic waste. The composting process involves turning the pile regularly to allow oxygen to mix with organic waste to maximize aerobic bacteria activity. 

This activity breaks down yard waste and food scraps, turning it into nutrient-rich soil. For this to happen, microorganisms need the right amount of heat, moisture, and air. 

Tips on How to Do Aerobic Composting Effectively

Tip 1: Setting Up a Composting Bin

Start by selecting a place for your compost bin that is well-drained and receives ample sunlight. You can use an available compost bin or create one using materials like chicken wire or wooden pallets.

In my article, Where To Place Your Compost Bin, I talk about the best spots and factors to consider for the right location of your bin. 

Also, if you’re unsure what composter you should use, check out my guide on Choosing a Composter.

Tip 2: Adding Composting Materials

Add a good mix of brown and green materials to your compost bin.

Brown materials such as dried leaves and twigs are carbon, while green materials like food scraps and grass clippings are nitrogen.

Aim for a ratio of 3:1 brown to green material.

Tip 3: Monitoring and Turning the Compost Pile

To ensure that your compost pile is working optimally, it’s important to check it regularly. 

Check the moisture level of the pile and adjust it as necessary by adding more carbon material or sprinkling with water. The compost pile should be moist but not too wet (think of the consistency of a wet sponge). 

Most importantly for an aerobic compost system, remember to turn the pile regularly to allow air to mix with the materials. This will speed up the decomposition process significantly compared to not turning it at all. 

Some composters like tumblers make this process easy, otherwise, revert to the tried and true method of using a garden fork.

The key to effective aerobic composting is to balance the composting process. Make sure that you have a good mix of brown and green materials, watch the pile’s moisture level, and turn the pile regularly. 

Different Types of Aerobic Composting

There are various methods of aerobic composting, each with unique advantages and disadvantages. Below are some of the most popular methods of aerobic composting:

Traditional Composting

Traditional composting is the age-old method of decomposing organic waste material into nutrient-rich soil.

The process breaks down food waste and yard scraps with the help of aerobic microorganisms that thrive when they have all the right conditions (moisture, air and heat).

These days there are many different traditional composters to suit everyone’s composting needs; whether it be small or large scale composting, low maintenance or hands on.

From compost bins to tumblers, I consider all of these in my beginners guide to choosing a composter.

You can put most waste materials into a traditional compost bin such as yard debris and food scraps, recycling them into nutrient-rich compost.

Hot Composting

Another method of aerobic composting is hot composting. This is when high temperatures are produced within the compost pile. This results in the faster decomposition of the waste materials and it is sometimes referred to as “thermophilic composting”. 

Hot composting usually takes several weeks or months to produce finished compost depending on the size of the pile and the type of organic waste. 

For microorganisms to thrive during the decomposition process, it’s important to maintain the right balance of nitrogen-rich materials and carbon (green vs brown material). You should also keep in mind proper aeration and moisture levels to ensure that you achieve a nutrient-rich compost.

Vermicomposting (aka Worm Farming)

Vermicomposting is another form of aerobic composting. It uses worms to break down organic waste, creating nutrient-rich compost known as worm castings. Worm farming is ideal for small-scale composting and can be done both indoors and outdoors.

The worms used in this process are red wiggler earthworms. Vermicomposting also produces little to no odor and can be done year-round. 

To learn more about vermicomposting to transform your organic waste into “black gold”, check out my articles on worm farming.

What is Anaerobic Composting

Anaerobic composting is composting (i.e. the decomposition of organic materials) without air. 

For anaerobic composting methods, the presence of air in the compost material actually slows down the decomposition process.

Anaerobic composting uses an enclosed or airtight container or pit to create an oxygen-free environment. This is ideal for the growth of anaerobic bacteria.  

Anaerobic composting doesn’t need to be turned or mixed regularly like aerobic composting methods. But, the decomposition process is slower.

Anaerobic methods of composting are helped by cutting up kitchen scraps or organic waste into smaller pieces to speed up the composting process.

Types of Anaerobic Composting

Anaerobic composting proves to be a useful method for turning your organic waste into nutrient-rich compost. There are several popular types of anaerobic composting methods, these are:

Bokashi Composting 

Bokashi composting is a method of anaerobic composting developed in Japan during the early 1980s. The method involves layering kitchen scraps with bokashi bran in a special air-tight bucket. 

Bokashi means “fermented organic matter”. By adding bokashi bran to kitchen scraps, it essentially pickles the food! Once the bucket is full, it’s left to ferment for a couple of weeks, after which time it can be dug into a trench in the vegetable garden. 

Bokashi provides amazing compost and is a great way of recycling ALL kitchen waste; bones, bread, food waste, just about everything! See this full list of what can be added to bokashi.

Bokashi also has a nutrient-rich by-product called bokashi tea that can be diluted and used as a fertilizer boost to water plants. 

You can learn all about bokashi in my Bokashi vs Compost article and Best Bokashi Bin Review, where I provide tips, and demonstrate how to do bokashi composting effectively.

Pit Composting

Pit composting is a method of composting where organic waste is placed in a hole or pit in the ground. Covering or sealing the pit restricts the flow of oxygen, creating an anaerobic composting environment. This then promotes the growth of anaerobic microorganisms that break down the organic material within the pit. 

Pit composting is a great ‘set and forget’ method of composting. Once it is in the ground, no further maintenance is required. It is difficult to harvest as it would have to be dug up, so pit composting is particularly useful in an area where you are looking to establish a new garden. 

Over time (can take 6 months or more), the organic material in the pit breaks down into nutrient-rich compost. This method of composting is generally slower and less efficient but can be useful in situations where space is limited. 

Once the pit is sealed it’s difficult to add more organic matter to it. For this reason, it’s also great in situations where one has a lot of organic material to get rid of all at once. Alternatively, you could dig lots of small pits rather than large ones. 

Tips on How to Do Anaerobic Composting Effectively

Here are some tips on how to do anaerobic methods of composting effectively:

Tip 1: Use a Sealed Container

Anaerobic composting requires a sealed container or pit to restrict the entry of oxygen. You can use a variety of containers, such as a plastic bin, a drum, large garbage can, or look at investing in a purpose-built Bokashi Bin.

Tip 2: Use the Right mix of materials

The right mix of materials is important for successful anaerobic composting. A balanced combination of green and brown materials (e.g. food waste, leaves, grass clippings, and shredded paper) will provide a good balance of carbon and nitrogen.

Tip 3: Add a Starter 

A starter or inoculant can help speed up the composting process by introducing beneficial bacteria and other microorganisms into the pile. You can buy a commercial compost starter, and use finished compost as a starter or bokashi bran.

Tip 4: Watch the Temperature

Anaerobic composting generates heat as the organic matter breaks down. If you want to see how things are progressing, use a thermometer to check the temperature of the compost pile and ensure that it stays between 100-140°F (38-60°C) for optimal composting.

Differences between Aerobic Composting and Anaerobic Composting

Here is a table summarizing the differences between aerobic composting and anaerobic composting:

Key Difference Between Aerobic Composting vs Anaerobic Composting

	Aerobic Composting	Anaerobic Composting
Oxygen	Requires oxygen for the decomposition process	Decomposes in the absence of oxygen
Temperature	Higher temperature is reached due to aerobic microbial activity	Lower temperature due to lower anaerobic microbial activity
Speed of Decomposition	Faster decomposition because of increased microbial activity	Slower because of less microbial activity
Smell	Produces a mild, earthy smell	Can produce a strong, sour odor that is unpleasant to some
End Product	Creates a crumbly, nutrient-rich compost	Creates an extremely nutrient-dense compost
Nutrient Content	Higher amounts of nitrogen due to aerobic decomposition	Lower nitrogen levels
Maintenance	Requires regular turning and monitoring	Low maintenance

While both composting methods have their advantages and disadvantages, anaerobic composting can be a better option if you have limited space. It’s possible to work on this with less equipment and in a smaller area. Whereas aerobic composting typically requires space to be able to turn the compost regularly.

Speed of decomposition is another key factor as it relies strongly on the level of microbe activity.

It’s worth noting that it is possible to have a traditional compost bin and not turn it regularly (admittedly this has been me in the past). The material does still break down but just at a much slower rate.

Pros and Cons of Aerobic Composting vs Anaerobic Composting

AEROBIC COMPOSTING		ANAEROBIC COMPOSTING
PROS	CONS	PROS	CONS
Produces compost faster	Requires more maintenance and turning	Low maintenance	Generates an odor if not managed
Generates hotter temperatures	Requires regular high levels of oxygen to be introduced	Less labor-intensive	Produces lower nitrogen compost that may not be suitable for all soil types
Produces less odor	Requires more space for air circulation	Requires less space and less equipment
More efficient at breaking down organic waste	Can be more labor-intensive	Can handle a wider variety of organic waste
Worm farming creates a nutrient-rich fertilizer byproduct called ‘worm tea’		Bokashi can take just 4 weeks to create a pre-compost. It also creates a nutrient-rich fertilizer byproduct called ‘bokashi tea’

Which Composting Method is Right for You?

Choosing the right methods of composting can be challenging, especially if you are new to composting and feel overwhelmed about where to start.

My advice is to simply follow the motto of The Potager Project and “start somewhere”. Gardening is always a case of testing and trying new things, so everything you try is an opportunity to learn.  

Both anaerobic and aerobic composting methods have their advantages and disadvantages. Aerobic composting requires oxygen and frequent turning of the compost pile to maintain optimal oxygen levels and heat. Thereby, making it a faster and more efficient process.

While anaerobic composting requires little to no maintenance and as an aside, produces methane gas which can be used as an energy source. It’s suitable for people who have less time on their hands to regularly turn a pile. The likes of bokashi composting is also great for those with a small garden or gardening in an apartment garden.

Deciding Factors When Choosing a Composter

Both composting methods have their benefits and drawbacks. The choice of which composting method to go with will depend on your personal preference and the resources you have available. If you have limited space, choosing an anaerobic composting method like bokashi or an aerobic composter like a worm farm would both be good options as they require less space.

If you have a larger space and a high volume of waste (e.g. lawn clippings, branches, etc) then a large traditional compost or pit compost could be the best option for you. 

There are options in both aerobic and anaerobic composting to suit every space and level of waste produced. I have summarized some of the key deciding factors below.

	AEROBIC COMPOSTING	ANAEROBIC COMPOSTING
Small space or apartment garden	Worm Farm	Bokashi Composting
A large amount of yard waste	Traditional Composting or Hot Composting	Pit Composting
Low maintenance	Tumbler (traditional composting)

Final Words on the Different Types of Composting

Composting is a great way to reduce waste, save money and improve the health of your plants and soil. Both anaerobic and aerobic methods of composting provide valuable advantages depending on your composting needs.  

Aerobic composting is typically faster and produces less odor, but generally need more maintenance and attention (to turn the compost regularly). 

Anaerobic composting is typically slower but require less maintenance and can break down more types of waste.

Regardless of which types of composting you choose, composting is a simple and effective way to make a positive impact on the environment and create nutrient-rich fertilizer for your vegetable garden.